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Ask for a consultationIndicative results, provided for preliminary estimation. They do not replace the design and verification of the real case by a qualified professional.
How to use it
Describe the load: for a rotating machine (table, roller, agitator) the resisting torque, speed and inertia; for a translating load (carriage, conveyor, hoist) the force, speed, mass and the diameter of the drum or pinion that turns it into rotation. Add acceleration time, transmission efficiency and service factor.
The tool calculates steady-state and peak power, picks the standard IEC frame size and compares 2, 4, 6 and 8-pole motors with the reduction ratio needed for each. If you specify a ratio, it chooses the most suitable number of poles.
Formulas used
Motor speeds are indicative at 50 Hz; the nameplate value depends on frame size and manufacturer. The start-up check compares the torque required at the motor shaft with the rated torque: standard induction motors can deliver about 1.6–2 times the rated torque at start-up, less if started star-delta.
What remains to be checked
The real duty cycle (continuous, intermittent, with frequent starts), ambient temperature, altitude, the motor's own inertia, braking and any inverter change the choice. Fast axes and positioning need servomotors, sized on the cycle's RMS torque. It's the sizing work we do in the automation and robotics service.
FAQ
What's the difference between power and torque?
Torque is the turning effort, power is torque times speed. For the same power, a slow motor develops more torque than a fast one: that's why a gearbox lets you use a small, fast motor on a slow, heavy load.
How many poles should I choose?
The 4-pole motor (about 1450 rpm at 50 Hz) is the most common and cheapest for a given power. 2 poles are for fast pumps and fans; 6 and 8 poles reduce the gearbox ratio on slow loads.
What is the service factor?
It's a multiplier that accounts for shocks, frequent starts and overloads compared with uniform operation. It's chosen based on the type of machine and daily operating hours.
Do I need to consider the motor's inertia?
Yes, especially with low reduction ratios or frequent starts. The rotor inertia adds to that of the load referred to the motor shaft and increases the acceleration torque.